[sclug] Mirror disks across machines like distributed RAID?

Dickon Hood dickon-ml at fluff.org
Wed Jan 6 16:18:03 UTC 2010

On Tue, Jan 05, 2010 at 18:42:35 +0000, Keith Edmunds wrote:
: On Tue, 5 Jan 2010 17:04:01 +0000, dickon-ml at fluff.org said:
: > I have had at work, and my conclusion is this: in all cases I've ever
: > seen, don't bother. Do it at the application layer instead: you'll save
: > yourself a hell of a headache, and a bundle of cash.

: You seem to be very against DRBD but without stating any real reason.

I don't mean to be: as I said, I have no experience of it.  I'm just not a
fan of HA disc; IME it's better to engineer your application so you don't
need it.

: In the case, for example, of an HA web server, putting the websites on a
: DRBD device seems straightforward and reliable. How would you propose
: doing that in the application layer (and saving the aforesaid bundle)?

HA webservers can usually be managed happily with the usual tricks:
clusters of machines, load balancers (if you insist), HSRP-alike failover,
virtual IP addresses and whatnot.  Or you can simply do what the BBC has
done for many years, and have a five-minute TTL on the DNS and ifconfig an
alias on another machine should one of the farm go down.  This sort of
thing isn't rocket science.

Dickon Hood

Due to digital rights management, my .sig is temporarily unavailable.
Normal service will be resumed as soon as possible.  We apologise for the
inconvenience in the meantime.

No virus was found in this outgoing message as I didn't bother looking.

More information about the Sclug mailing list